Electroreduction of CO2 to syngas with controllable H-2/CO ratios in a wide potential range over Ni-N co-doped ultrathin carbon nanosheets

The conversion of CO2 to syngas (H-2 and CO) via electrochemical reduction has been considered a promising strategy to mitigate the greenhouse effect. However, it is a great challenge to control H-2/CO ratios over a wide voltage window. Herein, a new method of fabricating Ni-N co-doped carbon nanosheets by molten salt-assisted pyrolysis, impregnation and re-carbonization is proposed. Benefiting from their ultrathin structure and tunable Ni-N-x active site content, the H-2/CO ratios can be adjusted from 1/2 to 2/1 within a wide applied voltage range (-0.7 to -1.3 V vs. RHE). After electrochemical stability testing for 10 h, the current density and H-2/CO ratios remained almost constant, revealing robust long-term stability. This work may benefit the construction of efficient and low-budget electrocatalysts for the production of tunable syngas.